The zombie drama "The Walking Dead" normally airs on the American cable-television channel AMC on Sunday evening.

But on Monday, residents of two small American cities got treated to a zombie apocalypse over the air, courtesy of pranksters who apparently hacked into the Emergency Alert System at three broadcast stations.

"Civil authorities in your area have reported that the bodies of the dead are rising from their graves and attacking the living," said an ominous voiceover that interrupted programming yesterday afternoon on KRTV-TV, a CBS affiliate in Great Falls, Mont., and on a KRTV subchannel that carries a CW network feed.